Predictive transmission shifting

Abstract

A vehicle transmission can perform predictive shifting. Road grade and vehicle path data can be employed to identify a future change in road grade such as a hill. A change in speed relative to a vehicle cruise speed can be estimated or predicted in view of the change in road grade and a current gear. If the change of speed is determined to be outside a performance bound, shift recommendation can be determined to maintain vehicle cruise speed within the performance bound. A controller can alter default gear selection of the transmission in response to receipt of the shift recommendation.

What is claimed is: 
     
       1. A system, comprising:
 a processor coupled to a memory that includes instructions that when executed by the processor cause the processor to:
 identify a future change in road grade based on road grade data and vehicle path; 
 predict a change in speed relative to a vehicle cruise speed that is outside a performance threshold based on the future change in road grade; 
 determine a shift recommendation to maintain vehicle cruise speed within the performance threshold;
 wherein the shift recommendation is based on a multiple of identified future changes in road grade and application of a fuzzy variable logic that modifies shift points for controlling a retarder based on a torque capacity of the vehicle; and 
 
 communicate the shift recommendation to a controller that alters gear selection of a transmission based on the shift recommendation. 
 
 
     
     
       2. The system of  claim 1 , further comprising instructions that cause the processor to identify a hill based on the road grade data and predicted change in vehicle speed in view of the hill. 
     
     
       3. The system of  claim 2 , further comprising instructions that cause the processor to identify existence of the hill when vehicle speed loss exceeds a predetermined threshold. 
     
     
       4. The system of  claim 2 , further comprising instructions that cause the processor to classify current vehicle position related to the hill and determine the shift recommendation based on the current vehicle position. 
     
     
       5. The system of  claim 4 , wherein the shift recommendation is to inhibit an upshift, when speed on the hill is estimated to drop below a minimum threshold in a next gear up in advance of an uphill section. 
     
     
       6. The system of  claim 4 , wherein the shift recommendation is to trigger downshift, when speed is estimated to stay below a minimum threshold for more than a predetermined minimum time in a current gear as the vehicle nears the hill. 
     
     
       7. The system of  claim 4 , wherein the shift recommendation is to inhibit a downshift when the vehicle is on the hill and the vehicle maintains a speed above a minimum threshold. 
     
     
       8. The system of  claim 4 , wherein the shift recommendation is to trigger a downshift when the vehicle is on the hill and vehicle speed falls below a minimum threshold. 
     
     
       9. The system of  claim 4 , wherein the shift recommendation is to inhibit a downshift when the vehicle nears a top of the hill. 
     
     
       10. A method, comprising:
 identifying a future change in road grade based on road grade data and path of a vehicle; 
 predicting a change in speed relative to vehicle cruise speed that is outside a performance threshold based on the change in road grade; 
 determining a shift recommendation to maintain vehicle cruise speed within the performance threshold;
 wherein the shift recommendation is based on a multiple of identified future changes in road grade and application of a fuzzy variable logic that modifies shift points for controlling a retarder based on a torque capacity of the vehicle; and 
 
 communicating the shift recommendation to a controller that modifies default gear selection of a transmission based on the shift recommendation. 
 
     
     
       11. The method of  claim 10 , further comprising identifying a hill based on the road grade data when the change in speed exceeds a predetermined threshold. 
     
     
       12. The method of  claim 11 , further comprising classifying position of the vehicle relative to the hill and determining the shift recommendation based on the position. 
     
     
       13. The method of  claim 12 , further comprising determining the shift recommendation to be to inhibit a downshift near top of the hill. 
     
     
       14. The method of  claim 12 , further comprising determining the shift recommendation to be to trigger a downshift in advance of an uphill section in which speed is predicted to fall below a minimum speed for a time that exceeds a threshold time. 
     
     
       15. A method, comprising:
 executing, on a processor, instructions that cause the processor to perform operations comprising:
 identifying existence and severity of a hill based on future road grade data and a vehicle path; 
 predicting a change in speed associated with the hill relative to a desired cruise speed that is outside a performance threshold and current gear; 
 determining a shift recommendation to maintain cruise speed within the performance threshold;
 wherein the shift recommendation is based on a multiple of identified future changes in road grade and application of a fuzzy variable logic that modifies shift points for controlling a retarder based on a torque capacity of the vehicle; and 
 
 modifying a default shift pattern of a transmission based on the shift recommendation. 
 
 
     
     
       16. The method of  claim 15 , wherein the operations further comprise determining the shift recommendation based on current position of the vehicle relative to the hill. 
     
     
       17. The method of  claim 16 , wherein the operations further comprise determining the shift recommendation to be a downshift in advance of an uphill section in which speed is estimated to fall below a minimum speed for a time that exceeds a threshold time. 
     
     
       18. The method of  claim 16 , wherein the operations further comprise determining the shift recommendation to be to inhibit a downshift near top of the hill. 
     
     
       19. The method of  claim 16 , wherein the operations further comprise determining the shift recommendation to be a downshift from the current gear on an uphill portion of the hill when speed drops below a minimum threshold speed. 
     
     
       20. The method of  claim 16 , wherein the operations further comprise determining the shift recommendation to be a downshift from the current gear in anticipation of exceeding a maximum speed on a downhill portion of the hill.